November 22, 2023
Stress, simply put, is a killer. Chronic stress affects the immune system and contributes to sustained inflammation in the body which impacts ocular health and contributes to ocular disease. The neuroendocrinology researcher, author, and professor of neurology and neurosurgery at Stanford University, Dr. Robert Sapolsky, is an expert on the deleterious impact of chronic stress on health. One of his most famous books, Why Zebras Don’t Get Ulcers, is an excellent guide to stress, stress-related diseases, and coping. The critical point of the book is as follows: “If you are that zebra running for your life, or that lion sprinting for your meal, your body’s physiological response mechanisms are superbly adapted for dealing with such short-term physical emergencies. For the vast majority of beasts on this planet, stress is about a short-term crisis, after which it’s either over with or you’re over with. When we sit around and worry about stressful things, we turn on the same physiological responses, but they are potentially a disaster when provoked chronically. A large body of evidence suggests that stress-related disease emerges, predominantly, out of the fact that we so often activate a physiological system that has evolved for responding to acute physical emergencies, but we turn it on for months on end, worrying about mortgages, relationships, and promotions.”
Chronic Stress as a Driver of Inflammation
Chronic stress increases inflammation in all organs of the body including the eyes. The exact mechanisms behind this process are complex and involve the interaction of the body’s stress response system (the hypothalamic-pituitary-adrenal axis or HPA axis), the immune system, and various signaling molecules.
- Activation of the HPA Axis: When stress is experienced, whether it’s physical, emotional, or psychological, the HPA axis is activated, releasing glucocorticoids such as cortisol from the adrenal glands. This cortisol release mobilizes energy reserves to ensure that the organism has the resources needed to meet a very real or predicted insult.1
- Immune System Response: Cortisol, one of the key stress hormones, plays a role in modulating the immune response. In the short term, cortisol can have anti-inflammatory effects, suppressing certain aspects of the immune system. However, chronic stress leads to dysregulation of the innate and adaptive immune responses by altering the type 1/type 2 cytokine balance, thereby inducing low-grade inflammation and suppressing the function of immune-protective cells.2
- Proinflammatory Cytokines: Prolonged stress can lead to an increase in the production of proinflammatory cytokines such as interleukin-6 (IL-6) and tumor necrosis factor alpha (TNFa).3
Chronic Inflammation Linked to Several Eye Diseases
Chronic inflammation secondary to long-term stress has been causally linked with increased risk for numerous diseases such as infectious diseases, cardiovascular disease, diabetes, certain cancers, autoimmune disease, uveitis, dry eye disease, macular degeneration, and glaucoma.4,5,6,7 One potential mechanism linking chronic stress and inflammation in the onset of a wide range of diseases is that prolonged stressors result in glucocorticoid receptor resistance, which, in turn, causes dysregulated HPA axis function and interferes with the appropriate regulation of inflammation.7,8 Decreasing systemic inflammation through lifestyle choices involves much more than our choice of what foods we eat. Evidence-based lifestyle practices exist that are proving to be powerful tools to mitigate the smoldering fires of inflammation brought on by the chronic stressors in our daily lives.
Mindfulness: An Antidote to Stress and Path to Well-being
Mindfulness is the practice of being fully present in each moment. It is an ancient Buddhist approach to living that teaches us to be in the here and now, aware of what is going on within us and around us from moment to moment, without judgment. It can be used to reduce stress, increase self-awareness, and cultivate a sense of acceptance and well-being.
Although an ancient practice, the scientific study of mindfulness is now mainstream with institutions such as Harvard’s T.H. Chan School of Public Health embracing it with its Center for Mindfulness. Housed in the Department of Nutrition at Harvard with the world-renowned nutrition researcher Dr. Walter Willett as the director, its mission is to pursue evidence-based approaches to improve well-being through mindfulness and educate and train the public in mindfulness. Mindfulness research is evidence based. For example, in a seminal study from 2011, Harvard-affiliated researchers at Massachusetts General Hospital studied the brain MRIs of participants before and after they underwent an eight-week mindfulness-based stress reduction (MBSR) program. They also compared their brains to a control group who didn’t go through the training. Researchers observed that, after engaging in mindfulness training, their brains indicated visible structural changes when compared to the controls. For instance, they noticed increased gray matter density in the hippocampus, a structure greatly affected by chronic stress and associated with storing memories and emotion control. They also discerned decreased gray matter in the amygdala, a structure associated with stress, fear, and anxiety including our fight-or-flight response. Interestingly, the less stressed out the subjects reported being, the smaller their amygdalas appeared to be.9
Mindfulness Meditation Can Impact IOP
For ocular health, mindfulness meditation has been shown to be an effective addition to glaucoma management. In one study involving 60 patients with ocular hypertension defined as IOP above 21 mm Hg, the participants were divided into two groups. One underwent six weeks of daily sessions of mindfulness-based stress reduction including breathing exercises and meditation techniques, while the other group received nothing. A significant decrease in IOP and stress levels in the meditation group as well as improved optic nerve head perfusion and quality of life were observed in the treatment group verses the control group.10 In another study published in the Journal of Glaucoma that included 90 patients with primary open angle glaucoma, one group practiced mindfulness meditation for 21 days, 60 minutes daily, while the other group did not meditate. The meditating group showed significantly lower IOP than the non-meditating group along with a significant reduction in stress-related chemicals and a significantly improved quality of life.11 This study also showed positively modified gene expression in patients with primary open-angle glaucoma. This research supports the potential role of meditation as an adjunctive clinical therapy for glaucoma treatment.
Burnout Prevention is Another Benefit
Mindfulness meditation is an effective way to avoid burnout for practitioners. Dr. Stuart Tasman, OD, who practices in Georgia and is the past president of the Georgia Optometric Association, uses mindfulness meditation to cope with everyday stressors. “Meditation is something I thought was simply for other people. All of my life I have dealt with the stress of running a practice, being a dad, being a husband, and being a boss. I never took medications, but I was starting to feel overwhelmed. I was introduced to the concept of mindfulness and thought ‘not for me,’ but for some reason I tried it. I listened to a meditation app and became intrigued. I took a 30-day challenge and my life changed. I focus so much better and deal with stuff without stressing like I used to. I believe it can be beneficial for all.” For practitioners interested in learning more about mindfulness meditation, please visit the website for the Benson-Henry Institute for Mind Body Medicine at Massachusetts General Hospital.
Comprehensive prevention and wellness involve more than just addressing what we eat. We must also consider the deleterious effects of the chronic stressors of our daily lives. Mindfulness meditation is emerging as an important intervention in healthy aging.
References
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2 Dhabhar FS. Effects of stress on immune function, the good, the bad, and the beautiful. 2014. Immunol Res: 193-210.
3 Black PH. Stress and the inflammatory response: a review of neurogenic inflammation. 2002. Brain, Behavior, and Immunity, 16(6), 622-653.
4 Glaser R, Kiecolt-Glaser JK. Stress-induced immune dysfunction: implications for health. 2005. Nat Rev Immunol 5:243-251.
5 Padro CJ, Sanders VM. Neuroendocrine regulation of inflammation. 2014. Semin Immunol 26:357-368.
6 Webster Marketon JI, Glaser R. Stress hormones and immune function. 2008. Cell Immunol 252:16-26.
7 Seiler A, Fagundes CP, Christian LM. The impact of everyday stressors on the immune system and health. 2020. In:Chouker A (eds) Stress Challenges and immunity in Space. Springer, Cham.
8 Cohen S, Janicki-Deverts D, Doyle WJ, et al. Chronic stress, glucocorticoid receptor resistance, inflammation, and disease risk. 2012. Proc Natl Acad Sci USA 109:5995-5999.
9 Holzel BK, Carmody J, Vangel M, et al. Mindfulness practice leads to increases in regional brain gray matter density. Psychiatry Res. 2011 Jan 30;191(1):36-43.
10 Dada T, Mondal S, Midha N, et al. Effect of mindfulness-based stress reduction on IOP in patients with ocular hypertension: a randomized control trial. Am J Ophthalmol. January 20, 2022.
11 Dada T, Mittal D, Mohanty K, et al. Mindfulness Meditation Reduces Intraocular Pressure, Lowers Stress Biomarkers and Modulates Gene Expression in Glaucoma: A Randomized Controlled Trial. Journal of Glaucoma 27(12):p 1061-1067, December 2018.
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